It's a question of preference to be honest. See if you can find a place to rent / shop to borrow / studio to try out and see which you prefer.
I've only used 1,2,3 and 5 personally.
I'm a big fan of the Neve style preamp, especially when paired with a U87, U67 or U47 on vocals. It's fat and rich, but nicely hard edged and present.
I liked he MA5, but the BAE and the Neve DPA stand out from that list for me.
The Avalon is a classic, but the preamp is a little soft for me. Also you're paying for a channel strip - the top end of the EQ is nice, but the compressor is only average. I wouldn't use that chain if I had choices.
Having said that I'm a bit of a Neve slut. For me part of the Neve sound is the EQ circuit in the original modules. If you only record vocals you may not need two preamps and could go for an actual Neve module or a BAE module strip.
If so, for me the daddy is the Neve 1084. It's a 1073 preamp with a more detailed EQ section... Seriously nice. BAE do a version as well as the Neve reissue.
My advice on most outboard gear however would be to try and find it second hand in good condition. If you buy it new from a shop it will lose 40% of its value the minute you walk out the shop
And if you can find an original vintage Neve 1084 in good condition it will actually keep going up in value!
If you're looking for a two channel interface the Apollo Twin is a good bet. It's reasonably priced, has good converters (not amazing but good) and is a good small desktop monitor controller. It also gives you a nice in to the UAD plugins, and zero latency monitoring through the plugins - the UAD 1176 after your preamp would be nice!
One of the best things about the Apollo Twin for me is its one of the few good small interfaces that has 2 inputs an 2 outputs as well as its monitor outputs. That means you can use outputs independent of your speakers, for example an analogue mix bus chain. This isn't true of the Apogee Duet for example, even though the converters are probably better.
I hope this helps.